Thanks!
I guess I'd qualify that partly by extending the time frame of 'initiation': I think it'll often be ethically justifiable to inflict violence on a person who tortured or killed one's partner, for instance, even if the potential to defend them, or to prevent that initial use of force, no longer exists. I think it'd often be ethically indefensible not to, in fact. I do know this inevitably leads to the death penalty, etc. but the problem there involves other things. I believe the intent and level of violence used or threatened ought to be informed by the details of the event, too.